Luteolin and its analog luteolin-7-methylether from Leonurus japonicus Houtt suppress aromatase-mediated estrogen biosynthesis to alleviate polycystic ovary syndrome by the inhibition of tumor progression locus 2.

ETHNOPHARMACOLOGICAL RELEVANCE: Leonurus japonicus Houtt (L. japonicus, Chinese motherwort), known as Yi Mu Cao which means "good for women", has long been widely used in China and other Asian countries to alleviate gynecological disorders, often characterized by estrogen dysregulation. It has been used for the treatment of polycystic ovary syndrome (PCOS), a common endocrine disorder in women but the underlying mechanism remains unknown. AIM OF THE STUDY: The present study was designed to investigate the effect and mechanism of flavonoid luteolin and its analog luteolin-7-methylether contained in L. japonicus on aromatase, a rate-limiting enzyme that catalyzes the conversion of androgens to estrogens and a drug target to induce ovulation in PCOS patients. MATERIALS AND METHODS: Estrogen biosynthesis in human ovarian granulosa cells was examined using ELISA. Western blots were used to explore the signaling pathways in the regulation of aromatase expression. Transcriptomic analysis was conducted to elucidate the potential mechanisms of action of compounds. Finally, animal models were used to assess the therapeutic potential of these compounds in PCOS. RESULTS: Luteolin potently inhibited estrogen biosynthesis in human ovarian granulosa cells stimulated by follicle-stimulating hormone. This effect was achieved by decreasing cAMP response element-binding protein (CREB)-mediated expression of aromatase. Mechanistically, luteolin and luteolin-7-methylether targeted tumor progression locus 2 (TPL2) to suppress mitogen-activated protein kinase 3/6 (MKK3/6)-p38 MAPK-CREB pathway signaling. Transcriptional analysis showed that these compounds regulated the expression of different genes, with the MAPK signaling pathway being the most significantly affected. Furthermore, luteolin and luteolin-7-methylether effectively alleviated the symptoms of PCOS in mice. CONCLUSIONS: This study demonstrates a previously unrecognized role of TPL2 in estrogen biosynthesis and suggests that luteolin and luteolin-7-methylether have potential as novel therapeutic agents for the treatment of PCOS. The results provide a foundation for further development of these compounds as effective and safe therapies for women with PCOS.

A small molecule inhibitor of caspase-1 inhibits NLRP3 inflammasome activation and pyroptosis to alleviate gouty inflammation.

Caspase-1 is an integral regulator of innate immunity, which plays a key role in inflammasome activation and the release of pro-inflammatory cytokines. The development of novel non-peptidic small molecule caspase-1 inhibitors is an important strategy for antagonizing excessively activated caspase-1 induced by inflammatory diseases, including gouty arthritis. In the present study, we identified 63 caspase-1 inhibitors, with different structures and potencies, from bioactive compound libraries. Among them, NSC697923 potently inhibited the enzymatic activity of caspase-1, with an IC50 value of 1.737 µM. This compound adopted a favorable conformation in the active pocket of caspase-1. Furthermore, NSC697923 potently decreased mature interleukin (IL)-1ß secretion in macrophages stimulated by lipopolysaccharide plus nigericin, ATP, and monosodium urate crystal. NSC697923 also inhibited NLRP3 protein expression by suppressing the NF-κB signaling pathway and the interaction between receptor interacting protein-2 (RIP2) and pro-caspase-1, thereby blocking the priming of the NLRP3 inflammasome. In addition, NSC697923 significantly inhibited caspase-1 mediated gasdermin D cleavage and pyroptosis in macrophages. In an animal model of gouty arthritis, NSC697923 effectively inhibited joint swelling, IL-1ß release, and NLRP3 inflammasome activation. Our results indicate that NSC697923 can effectively suppress NLRP3 inflammasome activation by inhibiting caspase-1, thus warranting further investigation as a potential therapeutic for treating NLRP3 inflammasome-related diseases.

Inhibition of Phosphodiesterase 5 Promotes the Aromatase-Mediated Estrogen Biosynthesis in Osteoblastic Cells by Activation of cGMP/PKG/SHP2 Pathway.

Mechanical stimulation induces bone growth and remodeling by the secondary messenger, cyclic guanosine 3', 5'-monophosphate (cGMP), in osteoblasts. However, the role of cGMP in the regulation of estrogen biosynthesis, whose deficiency is a major cause of osteoporosis, remains unclear. Here, we found that the prenylated flavonoids, 3-O-methoxymethyl-7-O-benzylicaritin (13), 7-O-benzylicaritin (14), and 4'-O-methyl-8-isopentylkaempferol (15), which were synthesized using icariin analogs, promoted estrogen biosynthesis in osteoblastic UMR106 cells, with calculated EC50 values of 1.53, 3.45, and 10.57 µM, respectively. 14 and 15 increased the expression level of the bone specific promoter I.4-driven aromatase, the only enzyme that catalyzes estrogen formation by using androgens as substrates, in osteoblastic cells. 14 inhibited phosphodiesterase 5 (PDE5), stimulated intracellular cGMP level and promoted osteoblast cell differentiation. Inhibition of cGMP dependent-protein kinase G (PKG) abolished the stimulatory effect of 14 on estrogen biosynthesis and osteoblast cell differentiation. Further, PKG activation by 14 stimulated the activity of SHP2 (Src homology 2 domain-containing tyrosine phosphatase 2), thereby activating Src and ERK (extracellular signal-regulated kinase) signaling and increasing ERK-dependent aromatase expression in osteoblasts. Our findings reveal a previously unknown role of cGMP in the regulation of estrogen biosynthesis in the bone. These results support the further development of 14 as a PKG-activating drug to mimic the anabolic effects of mechanical stimulation of bone in the treatment of osteoporosis.

[Exploration and analysis of theories of five phases, eight trigrams and four elements].

The theory of five phases is significantly different from that of eight trigrams of I Ching (Book of Changes): the eight trigrams represent the materials or phenomena in the nature, whereas five phases put "metal" created by human activities into nature, which organically incorporate the human activities and all the things in the nature and promote the formation of holistic concept of heaven and human being. Without the attendance of man, earth can't generate metal, metal can't restrict wood, and metal can't generate water. So, it can be concluded that the five phases is the improved eight trigrams. Together with monism of original qi and the dualism of yin-yang, it contributes to Chinese medicine the scientific world view and methodology to shake off wizards, and is also the root cause for the Chinese medicine being good at resolving complicated problems. The theory of five phases is also significantly different from the theory of four elements in the western world: The five phases create the relationship of the interaction and interrelation among everything on earth and is the embryo and basis of systemic science. The theory of four elements belongs to constructivism and is the sprout of analytical science.